Author Topic: gasoline/petrol ethanol question  (Read 5031 times)

Worsted Skeins

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gasoline/petrol ethanol question
« on: December 17, 2012, 09:26:44 AM »
A couple of independently owned gas stations in my area are advertising "ethanol-free" fuel.  The place where I refueled today had a note on the pump "may contain up to ten percent ethanol".  Other places (particularly along interstates) I have noted sell fuel labeled at the pump as E-15.  AAA issued a warning that E-15 could damage older cars.

What say the experts among us?  Is it wiser to pay a few pennies more per gallon for ethanol-free fuel or is this car model dependent?

Thanks in advance.

Blackbomber

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Re: gasoline/petrol ethanol question
« Reply #1 on: December 17, 2012, 09:43:35 AM »
Damage potential aside, I believe any properly running modern auto will get better fuel economy with the lowest possible ethanol content. Therefore you might find you actually spend LESS by buying undiluted fuel. In my case, this is true.

I don't have sources to back up my claims, but there is plenty of talk on this subject over on ecomodder.com. I'm pretty certain all of the evidence there is anecdotal. There is the suspicion of big money between the fuel companies and the government who mandates "oxygenated" fuel during winter months in certain locales. Therefore it may take some research to find any trustworthy information on this (or it simply doesn't exist). But I know how my MPG changes every fall and spring. During the warmer months I have a choice. In cooler, I do not.

Worsted Skeins

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Re: gasoline/petrol ethanol question
« Reply #2 on: December 17, 2012, 09:48:59 AM »
Damage potential aside, I believe any properly running modern auto will get better fuel economy with the lowest possible ethanol content. Therefore you might find you actually spend LESS by buying undiluted fuel. In my case, this is true.

I don't have sources to back up my claims, but there is plenty of talk on this subject over on ecomodder.com. I'm pretty certain all of the evidence there is anecdotal. There is the suspicion of big money between the fuel companies and the government who mandates "oxygenated" fuel during winter months in certain locales. Therefore it may take some research to find any trustworthy information on this (or it simply doesn't exist). But I know how my MPG changes every fall and spring. During the warmer months I have a choice. In cooler, I do not.

Yes, it seemed that much of the information I found was anecdotal.

I don't believe that I live in an area with reformulated seasonal fuels. My friends in the Midwest call these "winter gas" and "summer gas".  Is "winter gas" only sold in places with the potential for extreme cold?

ketchup

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Re: gasoline/petrol ethanol question
« Reply #3 on: December 17, 2012, 09:52:53 AM »
It matters most with older cars, but it is my experience that the best gas mileage always comes from no-ethanol fuel.  Pretty much every gas station in my area (Chicago suburbs) has E10 (10% ethanol) gasoline.  A few months back, I filled up in Missouri at a station without ethanol, and I got 10% better fuel economy on that tank (57MPG vs my running average before that of 52).  My car is a 1988, so with newer cars I'm sure the difference isn't as extreme, but in my case, the ethanol is pure filler in my gas tank.

I'd say see what works best for your own car, and then do some math.  If the extra price of the ethanol-free gas is offset by fuel savings, go for it.  If not, I wouldn't bother.  If it comes out about the same, I'd say go for the real gas. It's probably better for your engine anyway.

As for 15% ethanol, I would stay away.  I know my owner's manual specifically states that more than 10% ethanol could be damaging.

The economics of burning food as fuel are a whole other can of worms...

happy

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Re: gasoline/petrol ethanol question
« Reply #4 on: December 18, 2012, 12:01:26 AM »
A few years ago here is Australia there was a big controversy over E10 with vehement for and against arguments, lots of brandishing "studies". Finally I followed the advice of my motoring association (NRMA) who concluded there was no problem as long as the model and year was suited to the product. They publish a long list...Older models are more likely to have difficulty with this fuel. My model car was deemed safe and I have used E10 for years without problems. I haven't checked the MPG highly accurately but on face value cannot perceive any difference.

big country

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Re: gasoline/petrol ethanol question
« Reply #5 on: December 18, 2012, 07:01:51 AM »
More worisome then your car is any small engines that you might have.  They seem to do worse on E10 then your car.  Most modern cars are designed to handle it, but I would pay for for "real" fuel if I could.

Many small engines (espcially older ones) don't like E10 at all, especially since the fuel tends to sit in them more then it does in your car.  Small engines meaning lawn mowers, push mowers, generators, chain saws, weed eaters, etc.   I've heard the ethanol can absorb water and cause your gas to get water in it, and I've also heard the issues of "gumming" up when you let ethenol fuel sit for a season unused.  If you aren't going to use it for your car, I'd recommend that fuel for any small engines espcially if they're older.

I have a garden tiller from the 1950's and the manual for it called for leaded fuel.  I cannot find it anywhere (of course) so I have to use lead substitue additive for the gas in that thing.  Also, it expects real gas and not ethenol gas which is hard to find too.

If you're having issues finding it, I'm pretty sure most marinas carry real gas and not the stuff with ethenol due to the tendency to attract moisture.

Hope this helps.

Matt K

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Re: gasoline/petrol ethanol question
« Reply #6 on: December 18, 2012, 07:27:51 AM »
Ethanol has less energy per volume than petrol. Using it will see a decrease in fuel economy. How much of a decrease will depend on a lot of things.

Ethanol has a lot of uses in fuel beyond "saving the planet" (something there is a great deal of argument over, particularly with corn based ethanol).
1- Ethanol is a very powerful solvent / cleaning agent. You can use high ethanol gas to keep fuel lines and injectors/carbs cleaner. I know of several motorcycle mechanics who clean carbs 'the easy way', but soaking them in a bath of pure ethanol over night.
2- Ethanol burns cleaner (no sulfur in it). Around here you can buy Sunoco (now PetroCanada) 94 octane gas which is a high Ethanol (E10) blend. This stuff both cleans very well and burns very cleanly. Run two tanks of it and pretty much any car will pass an Ontario Emissions test according to a friend who owns a car dealership.
3- Ethanol also lowers the freezing point of petrol. Which means that it is often added to "winter gas" to prevent gas lines from freezing. Even in pure 'petrol' blends, they have to add something to prevent freezing in winter climates, and whatever they add does reduce fuel economy (one of the multitude of reasons why fuel economy gets worse in the winter).

When not to use an Ethanol blend?
1- Some engines just don't run as well on the stuff. My 2004 Mazda6 V6 (3.0L Ford V6, same as used in the Taurus of that year) would get 2-3L/100km worse mileage on E10 gas than I would from pure petrol; going from 10L/100km (23mpg) to 12L/100km (19mpg) with no other change. It was very consistent with this (I tracked every tank). But, I have not had such extreme differences with any other car I've owned. In fact my '92 Mazda 323 ran better on E10.

2- Old fuel lines. As mentioned, ethanol is a great cleaner. To the point where it will eat through fuel lines and gaskets designed for petrol only. I don't think this is a problem for any car sold in Canada since at least the 80s (we've been using Ethanol in our winter gas for at least that long). This is more a problem for classic cars. The other solution is just to replace the fuel lines with something modern.

3- Plastic fuel tanks. I do not know of a single car that uses plastic fuel tanks, but they are not uncommon in motorcycles. Depending on the plastic, the ethanol can cause warping and eventual leaking of the tank. The only motorcycle I know of for sure that suffers this problem is the Ducati MultiStrada 1000. Ducati issued a recall where they would replace warped tanks with an original tank (which sucked for owners, because it just meant that the tank would eventually warp again). Since a Ducati isn't a very Mustachian vehicle, I doubt it'll be a big issue for most here (my Dad however owns one of the affected bikes, hence why I know about it).

4- E15. Many governments mandated that cars be able to handle E10 long ago. So fuel systems can handle it. E15 was introduced much more recently, and I believe without the consent of the auto industry. I recall reading a number of executives were upset because they expect it will damage their fuel systems which were only rated for E10. I would read your owners manual carefully. Mine specifically states not to use higher than E10. I would follow the advice of your owners manual.

So, in summary - yes Ethanol will most likely lower your gas mileage. How much will depend on a lot of things, it could be a lot (4mpg) or it could be virtually indistinguishable from other factors. It could even help if you are running an old high mileage engine. If you are running a classic car with old fuel lines, avoid it. Check with your owner's manual or contact your car's manufacturer (I'd go head office, not dealership) to find out about E15 before using it regularly.

Worsted Skeins

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Re: gasoline/petrol ethanol question
« Reply #7 on: December 18, 2012, 08:14:18 AM »
So, in summary - yes Ethanol will most likely lower your gas mileage. How much will depend on a lot of things, it could be a lot (4mpg) or it could be virtually indistinguishable from other factors. It could even help if you are running an old high mileage engine. If you are running a classic car with old fuel lines, avoid it. Check with your owner's manual or contact your car's manufacturer (I'd go head office, not dealership) to find out about E15 before using it regularly.

Wow--thanks Matt for the informative post!

chucklesmcgee

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Re: gasoline/petrol ethanol question
« Reply #8 on: December 18, 2012, 09:37:06 AM »
So, in summary - yes Ethanol will most likely lower your gas mileage. How much will depend on a lot of things, it could be a lot (4mpg) or it could be virtually indistinguishable from other factors. It could even help if you are running an old high mileage engine. If you are running a classic car with old fuel lines, avoid it. Check with your owner's manual or contact your car's manufacturer (I'd go head office, not dealership) to find out about E15 before using it regularly.

Wow--thanks Matt for the informative post!

Yeah, it's basic chemistry/physics. Ethanol has a lower energy density than ordinary gasoline.  So gallon for gallon, straight gasoline is going to give you better mileage than E10 or E15 as there's more energy available in a gallon of pure gas than an gallon of ethanol-blended gas. Ethanol has been really subsidized by the government so I'm not quite sure from a pure mileage perspective if straight gasoline is cost effective.

Ditto for high octane fuels. Octane has a lower energy of combustion per volume than hectane, so the higher octane fuel you use, the lower the mileage you'll get. Of course if your car is actually designed for a high octane fuel you should use it to prevent knocking and engine damage.

frugal_engineer

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Re: gasoline/petrol ethanol question
« Reply #9 on: December 18, 2012, 09:45:03 AM »
Fuel mileage differences are due to energy content differences in the ethanol molecule vs those in gas (which is much more than just octane)

Ethanol has around 66% as much energy per volume as gasoline (http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent).  So in E10, with 10% of each gallon being ethanol, there is 1 - (10% * 66%) = 93.4% as much energy in a gallon than in pure gasoline.  You can expect 6% better gas mileage from pure gas vs E10.

That is pretty minimal.  When you really get a mileage penalty is when you use E85 or E100.  Then you're really lower on energy content vs gas.

If your pure gas stations have less than 6% higher cost then youre probably better off with pure.  Otherwise stick with E10.
« Last Edit: December 18, 2012, 09:47:40 AM by cvh8601 »

eyePod

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Re: gasoline/petrol ethanol question
« Reply #10 on: December 18, 2012, 10:07:21 AM »
The gas with ethanol is 3% less efficient on a fuel basis.  I just look at the gas price and multiply by 1.03 if I want to compare to a gas station that doesn't have it.  Speaking of, i couldn't figure out why my gas mileage isn't as good.  This is most likely the reason as the only local gas station on my way to work only has the ethanol crap as an option.

Posthumane

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Re: gasoline/petrol ethanol question
« Reply #11 on: December 18, 2012, 02:08:44 PM »
I have a garden tiller from the 1950's and the manual for it called for leaded fuel.  I cannot find it anywhere (of course) so I have to use lead substitue additive for the gas in that thing.  Also, it expects real gas and not ethenol gas which is hard to find too.
If you want to get leaded fuel for older engines that are designed to run it, go grab a few litres (or gallons) of 100LL from your local small airport. This is 100 Octane "Low Lead" aviation fuel. The "low lead" part means it has much less lead than older 100/130 AVGAS, but it is still about four times as much tetraethyl lead as standard automotive gasoline used to have.

Apart from the great points that Matt K mentions, there are a few other issues with ethanol blended fuels:
1. Ethanol is hygroscopic, meaning it attracts and blends with water vapour in the air. The result is that you get a puddle of water/ethanol mix at the bottom of your tank which can cause a variety of issues, especially in vehicles that sit for longer periods. In fact, the way to test for ethanol in your fuel is to take a test tube or similar container, fill it with a small amount of water up to a known mark, top the rest up with gasoline, shake it around, then see if the apparent water level has increased a significant amount.
2. Ethanol is more volatile than many other components of gasoline (i.e. it has a higher vapour pressure). This means that at high altitudes and higher temperatures it will evaporate more quickly than many other elements in gasoline which leaves you with less fuel and with a different composition. The evaporation can lead to vapour lock in vehicles with fuel lines that are not under pressure (carburetted cars). This is why you shouldn't use "winter gas" in the summer time in regions where they make the switch, and why it is not allowed in piston powered aircraft.